A halohydantoin compound has been widely used as a sensitizer for a photograph or the like or as a halogenating agent or an oxidizing agent for use in a process of producing a medicinal product, an agricultural chemical, a compound, or the like.
In particular, 1,3-diiodo-5,5-dimethylhydantoin is considered as a promising compound, as 1,3-diiodo-5,5-dimethylhydantoin is high in iodine content and an economical method for producing 1,3-diiodo-5,5-dimethylhydantoin has been disclosed.
As a method for producing 1,3-diiodo-5,5-dimethylhydantoin, for example, a method including the step of causing 5,5-dimethylhydantoin and iodine monochloride to react with each other in the presence of a base in a mixed solvent of an aqueous solution of a base and an organic solvent and a refining method have been disclosed (see, for example, Patent Literature 1 and Non Patent Literature 1).
Non Patent Literature 1 describes the following method: First, 5,5-dimethylhydantoin and iodine monochloride are reacted with each other with use of a sodium hydroxide aqueous solution and carbon tetrachloride. Next, the resulting crystals are washed with water, and are further washed with anhydrous ethyl acetate. After that, the crystals are dried at 60° C. under reduced pressure, whereby 1,3-diiodo-5,5-dimethylhydantoin is refined. Non Patent Literature 1 states that the resulting 1,3-diiodo-5,5-dimethylhydantoin is a reagent which can be preserved in a desiccator in a dark place without requiring a recrystallizing step.
Further, Patent Literature 1 gives the following description: First, 5,5-dimethylhydantoin and iodine monochloride are reacted with each other in a sodium hydroxide aqueous solution with use of N,N-dimethylformamide or an n-butyl acetate solvent. Next, the precipitated crystals as a result of the reaction are collected by filtration, and then dried under reduced pressure, thereby being refined.